People hate me for talking like this, & even got shamed out of the Sheik Skype chat because I guess it made people insecure & they started to say I have Aspergers & am ******** & ****, which I am not & do not. I just love Smash philosophy. So here's a heads up; if you want to skip my post & not challenge your Smash paradigm in simple ways, go ahead. Just being a tad bit abstract here, I do not mean to sound condescending at all. Abstract conjecture in Smash always helps me the most in more overarching ways than technical advice. So don't take any of this the wrong way, it's not necessarily YOUR question I'm answering but the question that just so happened to be proposed by you. In any case, I still hope it helps. 
Abstraction 1: The importance & advantage of PACE & more in depth look @ music.
Listening to music during the match helps a lot of pros. You'll notice almost everyone has ear buds in probably playing their favorite inspirational songs. Tho I'd suggest something soothing & not exciting, like Beethoven or Mozart. Seriously consider this, but try out different ones. Something mundane will get your nerves moving slower, which is what you need to not over-stress your concentration. When your heart goes too fast, that's when ppl move around too much & miss your queues to act or punish.
Reaction time windows AREN'T for reacting. Reacting is for afterwards. The window itself is for REMAINING CALM. Remember that & you'll have constant little "breaks" that will actually help your game play. If you start dash dancing for no other reason than not wanting to stand still, that's a mistake. You want to STAY STILL, unless you know FOR SURE why you shouldn't. You'll now have the proper advantage of that reaction window. Don't lose that advantage.
So; CALMING music. Though anything loud enough to drown out chants & cheers. Unless you main fox & need 24/7 techno music to keep your heart beating. lol i kid. I'm a joke maker. Anyway..
Don't get it backwards my friends, EVERYBODY gets those jitters. To find a way to not get them, is only going to upset you when you can't. You've probably heard the idea that fear is good? It's fight or flight. YOU WANT THOSE JITTERS. They will only effect you negatively when you think those feelings are because you think you'll lose. Just keep remembering the more you have jitters the more responsive your body is becoming WITHOUT thinking. THIS is the part you recognize you need control over. Take advantage of it by letting yourself know it's just your body letting out steam. Because you're being steam powered baby & you're on a roll!
OK Abstraction 2: No special titles allowed.
You're already well on your way to ignoring your opponent as a person, which is the point. You want to stay IN the game, so face your adversary as though he's a CPU. Not just a CPU though, but the roster character he's playing.
It's a lot easier facing a character than a person. Thinking too much about the person will give you false ideas about their game ability. REMEMBER they're not a person, they're a person controlling a very limited & vulnerable video game character. Example: You're not facing Mango, you're facing fox. Mango might not have weaknesses in his personality (tho I strongly BEG to differ), but on the other hand, FOX has PLENTY of listed & ordered weaknesses. Just remember that. & one more time: Jitters are GOOD. But don't delve too long on them, nor try to "summon" them. Just make the conscious realization that it needn't cause you distractions.
People are correct in that this will all come naturally in time. Tho this is how your brain works it out. Don't worry if your hands are shaking uncontrollably after you win or lose or fumble for your controller or crack your voice lol. Your living the dream dude! Shaky hands or not. People are putting themselves in YOUR position on the learning curve, not vice versa. So enjoy it. They won't say it, but they believe in you to only get better more & more the worse you play.
Abstraction 3: I can has thought provocation?
Read everyone's suggestions above, they are pretty spot on.
But also: READ THIS WALL of text.
Ask for more advice if you need but be sure to be more specific.
Critique on video:
You're doing fine. You are spacing away very well to avoid his flurry of approaches & VERY GOOD at ground maneuvering & control. I can only suggest taking more chances in attacking again faster. If jitters was your problem in that first match vs CF, I'd wager you played it safe & it paid off, but you forgot to drop the playing it safe once you had the advantage. In any case, even if I'm wrong about that, it is the worst symptom if nerves; not taking your advantage when it's yours.
